1.5 mv drop over Fuse No. 1

Hi all
1998 4.6HSE RangeRover GEMS engine.
The battery drain problem seems to be getting worse and worse, so rather than blame the ever awake alarm I thought I'd run a few further checks.
So with door latch closed (and door open) I set the alarm and waited for 30 mins and crept back to the garage trying not to wake the damn thing up.
Voltage drop over fuse 1 was 1.5mv and according to my chart this suggests a current draw of 128ma. All other fuses were showing zero voltage drop.
Fuse No 1 is the one marked with a gauge and I assume is the instrument cluster?

Any clues on where next or what this might be?
Also looking for a Nanocom for the GEMS engine if anyone has one for a good value price.

Thanks in anticipation.

I’m guessing that is the BeCM current draw whilst asleep. At that current draw it should take about 500 hours to flatten the battery.

Marshall8hp said:

I’m guessing that is the BeCM current draw whilst asleep. At that current draw it should take about 500 hours to flatten the battery.

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I wish. 72 hours is about the maximum I can leave it.

Is your battery good and healthy and what capacity is it?
Take the battery off and give it a full charge, leave it over night and see what voltage it holds

Typical battery drain with car properly asleep is usually 30-50mA total as long as the RF receiver doesn't wake up the BECM.

1. How long did you monitor the F1 current for ? (Better to buy a DC Current clamp and measure amps on the wiring.) This one from Amazon is what I use.
2. Have you replaced or disconnected the RF Receiver, or installed one of Marty's RF Filter boxes ?
3. Location in your profile might help know if there's anyone near you with Nanocom, although the nano will not help find battery drain !!

pwood999 said:

Typical battery drain with car properly asleep is usually 30-50mA total as long as the RF receiver doesn't wake up the BECM.

1. How long did you monitor the F1 current for ? (Better to buy a DC Current clamp and measure amps on the wiring.) This one from Amazon is what I use.
2. Have you replaced or disconnected the RF Receiver, or installed one of Marty's RF Filter boxes ?
3. Location in your profile might help know if there's anyone near you with Nanocom, although the nano will not help find battery drain !!

Click to expand...

Or Brian's second fob option, I've been using it for years.

kermit_rr said:

Is your battery good and healthy and what capacity is it?
Take the battery off and give it a full charge, leave it over night and see what voltage it holds

Click to expand...

Brand new 700 CCA. Thanks

pwood999 said:

Typical battery drain with car properly asleep is usually 30-50mA total as long as the RF receiver doesn't wake up the BECM.

1. How long did you monitor the F1 current for ? (Better to buy a DC Current clamp and measure amps on the wiring.) This one from Amazon is what I use.
2. Have you replaced or disconnected the RF Receiver, or installed one of Marty's RF Filter boxes ?
3. Location in your profile might help know if there's anyone near you with Nanocom, although the nano will not help find battery drain !!

Click to expand...

Hi

1. Went back and checked the voltage drop several times. I have a clamp ammeter but you can't isolate the wire from fuse 1. Check on the negative lead on the battery showed the same current draw. I tracked it down to fuse 1 from the BECM.
2. RF antennae is disconnected and has been for the last 10 years . Where do I get one of Marty's boxes?
3. Invercargill New Zealand and I want the Nanocom to track an HEVAC fault. Thanks

tomcat59alan said:

Or Brian's second fob option, I've been using it for years.

Click to expand...

What is Brian's 2nd fob option? Would love to find a new blank key plus fob but they seem to be like hens teeth!

Tasman said:

Brand new 700 CCA. Thanks

Click to expand...

I have a healthy 720cca in mine which is to be replaced in the week. If I have one glow plug that drops out and I miss the first crank the battery will drain unbelievably fast. Put the 700cca to one side and get an mf31-1000 Hankook battery then you'll see a difference in the car. Also check behind the kick panels in the footwell, if there is corrosion and damp the plugs want cutting out and the wires soldering. These cars are wired live and any damp can create a draw especially from damp plugs on the interior.

Tasman said:

Hi

1. Went back and checked the voltage drop several times. I have a clamp ammeter but you can't isolate the wire from fuse 1. Check on the negative lead on the battery showed the same current draw. I tracked it down to fuse 1 from the BECM.
2. RF antennae is disconnected and has been for the last 10 years . Where do I get one of Marty's boxes?
3. Invercargill New Zealand and I want the Nanocom to track an HEVAC fault. Thanks

Click to expand...

The nanocom is a great tool for the 38'.

Petrol doesn’t struggle without 1000cca like the diesel.
If becm wakes up you can see it in the night as the light near prindle stick illuminates when it wakes. Only works with an auto obviously

Tasman said:

What is Brian's 2nd fob option? Would love to find a new blank key plus fob but they seem to be like hens teeth!

Click to expand...

I got a remote"jog" switch off eBay and wired it in next to the RF receiver.i simply cut the wire from the receiver to the becm so unless the jog switch is activated any spurious signals received cannot be passed on .Hope that makes sense.

Here you second fob mod
https://www.landyzone.co.uk/land-rover/rf-reciever-work-round.258096/#post-3078662

Just unplug items that are fed by F1, and measure again.

Mark Piercy said:

I have a healthy 720cca in mine which is to be replaced in the week. If I have one glow plug that drops out and I miss the first crank the battery will drain unbelievably fast. Put the 700cca to one side and get an mf31-1000 Hankook battery then you'll see a difference in the car. Also check behind the kick panels in the footwell, if there is corrosion and damp the plugs want cutting out and the wires soldering. These cars are wired live and any damp can create a draw especially from damp plugs on the interior.

Click to expand...

Hi. So looking at the components associated with Fuse 1, you suggest any of the connectors rather than an actual component? I was thinking about the centre console switching unit.

pwood999 said:

Just unplug items that are fed by F1, and measure again.

View attachment 240948

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Thanks. That was my plan, I was hoping someone would say "oh its the widget on the doodad" that I could try first without too much dismantling. I think it will be the centre console switching station.